1. Field of the Invention
This invention pertains to a compliance mounting arrangement for a scroll fluid device that permits one scroll to move relative to a cooperating scroll and relative to a support structure to accommodate pumping disturbances or misalignment between the scrolls or between the one scroll and the support structure.
2. Background of the Prior Art
Scroll fluid devices are well known and operate on the principle of relative orbiting, intermeshing, axially, extending involute-shaped scroll flank members creating periodically and progressively closing or opening chambers during the orbiting process to thereby achieve a pumping or driving effect, depending upon the direction of fluid flow and the energy input into the system. While the scroll elements will always orbit relative to each other, in some instances both scroll elements can rotate together simultaneously with the orbital movement, such scrolls being herein referred to as "co-rotating", or one scroll can be driven in an orbital sense relative to another scroll that is held in a fixed position, the latter being referred to as non co-rotating for convenience. In either case, energy input typically will occur through a driving or drive scroll, and the other scroll will react the driving energy imparted through or resulting from the motion of the driving scroll. In some cases, both scroll elements in a co-rotating system can receive input energy and will therefore both be driven by the input energy. In some scroll fluid devices, one of the scrolls may tend to become misaligned relative to its mating scroll or its support structure due to various dynamic influences, including fluid and bearing forces acting on the scroll. This can result, for example, in a tilting of the axis of symmetry (generating axis) of one scroll relative to the other at an angle that can vary based on different operating conditions of the scroll device or a tilting of a scroll relative to its support bearing. Such relative angular orientation of the axis of a scroll element is undesirable both within the primary fluid circulation area of the scroll elements and at the bearings supporting the scroll elements. Usually, in the prior known devices, such misalignment either is held to a minimum or, is tolerated, or large oversize bearings are used to react the forces tending to cause the misalignment.
When scroll fluid devices are intended to function as liquid refrigerant compressors, it is often desired to provide radial compliance between the scroll flanks that enables the flanks to open slightly to provide relief of forces generated when a liquid slug of refrigerant is ingested by the compressor. It is therefore highly desirable to provide a mounting system for scroll elements of a scroll fluid device that will compensate for misalignment between the axes of symmetry of the scroll elements or misalignment of one scroll relative to its bearing, while at the same time providing radial compliance for the system that permits the scroll flanks to open momentary when high forces are encountered between the flanks. More specifically, it would be highly desirable to provide a compliance mounting arrangement for at least one of the scroll elements that would enable continued precise alignment between the axes of symmetry of the meshing scroll elements even though the scroll elements become slightly misaligned relative to their supporting housing or bearings while at the same time accommodating slight radial movement of one scroll relative to its mating scroll to enable the scroll flanks to open momentarily to accommodate a slug of liquid or to accommodate any other impediment to small clearances between the scroll elements.
Two types of compliance mounting arrangements useful in scroll fluid devices are described in U.S. Pat. Nos. 2,324,168 and 4,435,137, wherein pivotable link connections between the scrolls maintain scroll flank contact during normal operation, but permit radial separation of the flanks upon the occurrence of excessive forces tending to separate the flanks. Both of these patented arrangements utilize a pivot rod which interconnects the scrolls at their respective centers of rotation.
U.S. Pat. Nos. 4,730,998 and 4,846,639 disclose additional scroll fluid devices known in the art which utilize a movable bearing support in order to provide a compliance mounting. The scroll fluid device disclosed in U.S. Pat. No. 4,730,998 includes a main bearing which journals the drive shaft of the apparatus and is capable of pivoting by small angles with two degrees of freedom. In U.S. Pat. No. 4,846,639, a movable bearing supports a driven scroll in a co-rotating system so that the driven scroll is biased in the radial direction in order to minimize gaps between wrap plates associated with the drive and driven scrolls.
These known compliance mounting arrangements, while solving some alignment problems associated with scroll fluid devices and while providing radial compliance to permit scroll flanks to open upon excessive pressurization, essentially fail to resolve these problems in a single unitary compliance mounting arrangement. In addition, many known compliance mountings for compressors are unreliable due to frictional factors. For instance, a compliance mounting mechanism which is based on mutual sliding of two cooperating scrolls will lock tight when a liquid slug substantially increases the force acting on the mechanism normal to the desired sliding direction.